Telephone signaling system



E. M. STAPLES TELEPHONE SIGNALING SYSTEM Filed June 21, 1932 May14, 1935.

Patented May 14, 1935Y 1 UNITED STATES PATENT OFFICE 2,001,039 TELEPHONE SIGNALING SYSTEM Elliot M. Staples,` llohokus, N. J., assigner to American Telephone and Telegraph Company, a corporation of New York i Y Application .rune-21, iseaseriai No. 618,519

v 9 Claims. (cina-i170) This invention relates to telephonesystems rhese ringers would be connected to the lines and more particularly to improvements in sigand to the echo suppressor circuits Vin such a naling arrangements associated with the lines manner that the operation of these ringers would of such systems. remove the short `circuit or open circuit ap- `V The signaling arrangements of the invention plied to the lineY by the operation of` the echo 5 are adapted for toll circuits in a .telephone syssuppressor or prevent the short circuit or open tem` when these circuits are equipped with decircuit from-being applied, thereby allowing the vices for the suppression of echoes. When used Signal t0 be DaSSed t0 the distant end 0f the with such circuits, they permit signals to be Circuit. Further details 0f the System may be 1o transmitted in both directions on the `circuit .more fullyunderstood from the detailed descrip- 1,0

simultaneously, thereby permitting any given option thereof hereinafter given. erator, for example, the operator originating The invention may be mOre fully understood the call, to completely supervise the call, Refrom the following description together with the call or disconnect signals could be transmitted aCCOmDanying draWing in Figures l, 2 and 3 0f by the originating operator and received at the which the invention is illustrated. Fig. 1 shows ,l5 distant endat the same time that switchhook a telephone circuit embodying the Signaling ar- -signals, audible ringing tone, busy signals, voice rangements at the terminals as Well as those of currents or other tones are being transmitted the invention. Figs; 2 and 3 show some alternaover the circuit in the opposite direction. The tive arrangements at the echo Suppressor point arrangements of the invention differ from other Of-COnneCting the Signaling apparatus t0 the Cir- 20 signalingsysterns in that they permit the sig- VCuit and EChO Suppressors. nais to be passed in the two directions simul- In Fig. 1.0i the drawing is Shown a telephon taneously over circuits which would otherwise be CrCuit L Connecting points A and B. tgether cui; one Way by the Operationvof an echo Sup- With `enough O the OperatOrS 00rd lClltS, I3

presser, Iand i3, toillustrate the operation of the signal- 25` As is well known in the art, echo Suppressors ing System. The line LiS 0f the Well-known fourare added to telephone circuits in order to pre- Wire type Comprising tWO Une-Way line SeCtlOnS, l vent .voice currents from being transmitted over and 2, for transmission in Opposite directions. the circuit in the two directions simultaneously. and might include the One-Way amplers A1, A2,

If this were not done, some of the current, re- A3, A4,A5 and A6. These lines would be connected `30 iiected back due to an irregularity, would enter to the line jacks,jll and 20, through the hybrid the talkers telephone, and if it was of sufficient coils 3 andi and networks N1 and N2, respecmagnitude and was delayed sufliciently by the tively, in a manner'Well knOWn in the art. Concircuit, he would hear an echo of his `own voice. neted t0 the tWO-Wre portion 0f the Circuit at Also, some of this delayed current would be repoint 2l would be sending ringer 5 and receiving 35 `ifiected again and be transmitted to the 1isteners ringer 6, and connected t0 the circuit at point 22 telephone and, if severe, would cause the lis- Would be sending ringer 'l and receiving ringer tener to hear an echo following the direct trans- 8. These ringers are of the well-known type, mission. For a full and complete discussion and the sending ringers being arranged so that dif` 40 illustration of echo Suppressors, reference is .ferent frequencies are transmitted in the two 40 made to an article by A. B. Clark and R. C. directions over the circuit, and the receiving Y Mathes in the Journal of the American'lnstiringerS ara arranged to be operated by the fretute of Electrical Engineers, June 1925, pages quency received from the distant end of the cir- 618 to 626. cuit and not by the local frequency. `In the In a signaling system, it is possible by means drawing, the sending ringer 51s arranged to send 45 well known in the art tov design the system so out 1400 cycles and the receiving ringer Bto rethat echo currents do not interfere with its opceive this frequency. Sending ringer 1 is areration. Thereforait is possible to disable the ranged to send out i000 cycles and receiving ringecho Suppressors while signaling. This is acer E to receive this frequency. At points 23 and complished by the arrangements of the4 inven- 24 of the circuit is connected echo suppressor S. 5,0 tion, which consist in providing receiving ringers This echo suppressor is of the Well-known type atthe echo suppressor points. These receiving ,comprising two amplifier detectors with relay ringers are arranged to be operated by cersystems arranged to short-circuit line 2 when tain signals but not bythe voice currents on voice or other currents are being transmitted other tones. in a manner well known in the art. k,over Vline l, Aand Vto short-circuit line I when 5? 3S. Vthereby blocking transmission of the signal from ldenote like-parts in both arrangements. arrangementsdiierin that in Fig. 2 one receiving transmission is over line 2. At points 25 and 26 of the circuit are connected receiving ringers l@ and H. These ringers are of the well-known type and are arranged to operate on both 1000 and MOO-cycle currents, but not on voice currents or other tones. The operation of these ringers at the echo suppressor point causes the short circuit, connected to the line by the echo suppressor, to be removed or prevents the short circuit from being applied.

With the signaling system shown on Fig. 1, when cord circuit I3 is connected to line jack I9 and relay 33 of sending ringer 5 is operated by closing ringing key Id, a MOO-cycle signal is ap plied to line I. This causes "receiving ringer ID connected to the line at point 25 to operate, which causes relay 2l to operate. The operation of this relay disconnects echo suppressor 8 from point 23 of the circuit. It also causes receiving ringer 8 connected to the line at point 22 to operate, which causes relay 33 to operate. The operation oi this relay causes the line lamp 3| to light. If at this time cord circuit I8 is connected to line jackZG and relay 35 of sending ringer 'I is operated by closing ringing key 3D, a 100G-cycle signal is applied to line 2. This causes receiving ringer ii connected to the line at point 26 to operate, which causes relay 28 to operate. The operation voi this relay disconnects echo suppressor 9 from point 2li of the circuit. It also causes receiving ringer 6 connected to the line at point 2| to operate, which operates relay 34. 'I'his causes cord lamp i5 to light.

Accordingly, it is seen that, by the arrangements oi this invention, the signals may be transmitted over lines I and 2 simultaneously, which would otherwise be impossible, as the signal from A to B over line l would cause relay 29 of echo suppressor 9 to operate, which would short-circuit line 2 at point 24, thereby blocking the transmission of the signal from B to A. Similarly, a signal sent from B to A wouldcause echo suppressor 9 to operate which would operate relay This would short-circuit line I at point 23,

A to B. If voice currents are being transmitted from A to B or from'B to A, receiving ringers I!) and II do not operate and the echo suppressor operates in the Vvregular manner to short-circuit line 2 if transmission is from A to B, and line I if transmission is from B to A.

When voice currents or tones other than the signal are being transmitted from A to B over line I, relay 29 of echo suppressor 9 operates to short-circuit line 2 at point 24. If at this time relay'35 of sending ringer l' is operated by closing ringing `key 30, the 1000cyclesignal is applied to line 2. As receiving ringer II is connected to the line in such a manner that the short circuit applied to the line by relay 29 does not affect the voltage applied to this ringer, relay 28 will be operated to remove the short circuit applied to the line at point 24. This allows the signal to be passed in the same manner as described above. 1t also prevents relay 39 of echo suppressor S from short-circuiting line I. The a1'- rangements of the invention would operate equally as well if voice currents were being transmitted from B to A at thesame time that a signal is passed from'A to B.

In Fig.- 2 is shown a modication of the arrangements'at the echo suppressor point of Fig. l. Similar reference characters have been utilized to The two ringer is used at the echo suppressor point in place of the two ringers of Fig. 1. The same results are obtained by the arrangements of Fig. 2 as of Fig. 1, by switching the receiving ringer, by means of relays connected to the echo suppressor, to the points in the circuit where it is required. In the arrangements shown by Fig. 2 the echo suppressor 9 is connected to lines I and 2 in the same manner -as in Fig. l. To the hali:` of the echo suppressor connected to point '23 are connected the windings of relays lli) and 4I in such a manner that the operation of this part of the echo suppressor will cause these relays to operate. With relays 4i! and 4I operated, the input of the receiving ringer Ii! is connected to point 26 of line 2, and the winding of relay 28 is connected to the output of the ringer. With relays 4D and H not operated, the input of ringer Ii! is connected to point 25 of line I, and the winding of relay 2l is connected to the output of the ringer.

When a signal is passed from A to B over line I, ringer I0 may operate before the echo suppressor operates, Yin which vcase relay 21 is operated, which prevents the echo suppressor from short-circuiting line 2 at .point 24, and a signal may be passed from B toA over line f2. If, when the signal is being passed from Ato B overfline l, the echo suppressor operates before ringer IU, line 2 is short-circuited at point 24 and relays 4E and 4I operate. If at this time a signal is Apassed from B to A over line 2, the ringer'connected to point 26 operates, which operates relay 2B. This removes the short circuit and allows the signal to be passed. This arrangement operates equally as well when al signal'ispassed'from B to A before a signal ispassed from A to B, or when a signal is passed in eitherdirection when voice currents or other tones are being passed in the opposite direction.

In Fig. 3 is shown a modiiication of Fig. 2. Similar reference characters have been used to denote like parts in both arrangements. The arrangement of FiggS differs from that of Fig..2 in that the receiving ringer lat the echo suppressor point is permanently connected to one of the lines. When voice currents, signals or other tones are passed from A to-B over circuiti, the echo suppressor operates to short-circuit line 2. VAsignal sent from B to A will operate ringer iD, and relay 28 will remove the'short circuit and the signal will be passed. A signalsent from B to` A will prevent the echo suppressor from short-circuiting line l and a signal may be passed from A tol?. at the same time. This arrangement differs from the arrangements of Figs. 1 and 2 in that when voice current or tones other than the-signals 4are being transmitted from 1B to A over line12, the

echo suppressor will short-circuit line I and'signals cannot be passed from A to B while these voice currents or tones are being applied.

In this description the sending and receiving ringers at the terminals are shown connected to the two wire portion of the circuit. This signaling system will operate equally as well if these ringers are connected to the fourwire portion of the circuit. This could be done by connecting sending ringers 5 and l' to the lines at the inputs to ampliers A1 and A6, respectively,`and receiv ing ringers' and 8 to the lines at the outputs to the amplifiers A2 andAs, respectively. Also, the

echo suppressor and receiving ringers at this point are shown connected to the iourewire portion of the circuit. This system would operate equally as well on a two-wire circuit.

Obviously, frequencies-0 1' 'combination :of frequenciesother. than 1000 or 1400 cycles could be used in the signaling arrangements of the invention. AThese frequencies have been referred to as desirable for purposes of illustration. Also, the relaycontact operated'by the receiving ringer at the echo suppressor point is shown connected to the line at the input to the half of the echo suppressor. connected to the same line as the receiving ringer. This system would operate equally as well-if `thisrelay contact were connected tothe line at theinput to the half of the echo suppressor connected to the other line. Accordingly, while the-invention has been disclosed as embodied in certain specific arrangements which are deemed desirable, itis understood that it is capable of embodiment in `many and other widelyV varied forms .without departing from the spirit of the invention as dened by the appended claims.

What is claimed is:

1.1Inr association with a transmission circuit, a transmission control system including an echo suppressor, means independent of the principal transmission over the circuit for applying thereto alternating current of certain frequencies,l

signal receiving circuit responsive to said certain frequencies and connected to said transmission circuit and to said echo suppressor, and

i switching means controlled thereby for disabling said echo suppressor by the operation of said signal receiving circuits.

2. In a transmission system, two one-way line sections for transmission in opposite directions, controlling means responsive to all currents in one of said line sections, switching means controlled thereby for disabling the opposite line section, means independent of the principal transmission over the system for applying to said first-mentioned line section alternating current of certain frequencies, av second controlling means associated with said disabled line section and responsive to currents of said certain frequencies, and switching means controlled thereby for permitting said currents of certain frequencies to be transmitted over said last-mentioned line section.

3. In a signaling system, two one-way line sections for transmission in opposite directions, a rst controlling means responsive to all currents in one of said line sections, switching means controlled thereby for disabling the opposite line section, means independent of the principal transmission over the system for applying to said first-mentioned line section alternating current of certain frequencies, a second controlling means associated with the rstmentioned line section and responsive to said currents of said certain frequencies, and switching means controlled thereby for preventing said rst controlling means from disabling the opposite lineV section.

4. In a transmission system, two one-way line sections for transmission in opposite directions, controlling means responsive to all currents in one of said line sections, switching means controlled thereby for disabling the opposite line section, means independent of the principal transmission over the system for applying to said first-mentioned line section an alternating current signal of arbitrarily chosen frequency, a second controlling means associated with said disabled line section and responsive to said alternating current signal, and switching means controlled thereby for permitting said signal to be transmitted over said last-mentioned line section.

5. In a transmission system, two Aonefway line sections for transmission in opposite directions, a iirst controlling means responsive to all.:l cur.- rents in one of said line sections;v switching means controlled thereby for disabling the opposite line section, means independentV ofotlie principal transmission over the system for ap'- plying to said iirst-mentioned line sectionwan alternating current signal of arbitrarily chosen frequencies, a second controlling meansy associated with said first-mentioned linesection and responsive to said alternating current signal, and switching means controlled thereby for;pre. venting said iirst controlling means .from diss abling the opposite line section..n i 6. In a transmission system, a one-way line section for transmission from A to B and another line section for transmission from B Vto A, a nrst `controllingsmeans associated with both line sectionsV and responsive .to f all currents, switching means controlled thereby for disabling the line from A to B when transmission is over the line from B to A, and for disabling the line from B to A when transmission is over the line from A to B, means independent of the principal transmission over the system for sending over either of said linesections an alternating current signal of arbitrarily chosen frequencies, a second controlling means associated with both line sections and responsive to said alternating current signals, and switching means controlled thereby for disconnecting the iirst controlling means from the line transmitting from A to B when said signals are transmitted in this direction, and from the line transmitting from B to A when said signals are applied to this line.

7. In a transmission system, a one-way line section for transmission from A to B and another line section for transmission from B to A, a rst controlling means associated with both line sections and responsive to all currents, switching means controlled thereby for disabling the line from A to B when transmission is over the line from B to A, and for disabling the line from B to A when transmission is over the line from A to B, means independent of the principal transmission over the system for sending over either of said line sections an alternating current signal of arbitrarily chosenV frequencies, a second controlling means associated with both line sections and responsive to said alternating current signals, and switching means controlled thereby for disconnecting the rst controlling means from the line transmitting from A to B when said signals are transmitted over said line, and from the line transmitting from B to A when said signals are applied to said line, said switching means controlled by said second controlling means being Vadapted to prevent the disabling of the line from B to A in response to energy in the line from A to B or to remove such disability if it has already been applied.

8. In a transmission system, a one-way line section for transmission from A to B, and another line section for transmission from B to A, a rst controlling means associ-ated with both line sections and responsive to all currents, switching means controlled thereby for disabling the line from A to B when transmission is over the line from B to A, and for disabling the line from B to A when transmission is over the lineV from A to B, a second controlling means responsive to certain signals and a switching means controlled by said rst controlling means for connecting said second controlling means to the line from A to B when transmission is over the line from B to A, and tov the line from B to A when transmission is over the line from A to B, and switching means controlled by said second controlling means for disconnecting said nrstmentioned controlling means from the line transmitting from A to B when said signals are transmitted in this direction, and from the line transmitting from B to A when said signals are applied to this line.`

9. In a transmission system, a one-Way line section for transmission from A to B and another line section for transmission from B to A, a rst controlling means associated with both line sections and responsive to all currents, switching means controlled thereby for disabling the line from A to B When transmission is over the line from B to A and for disabling the line from B to A when transmission is over the line 20 from A to B, means independent of the principal transmission over the system for sending over either of said line sections anv alternating current signal of arbitrarily chosen frequencies, a second controlling means associated with both line sections and responsive to said alternating current signal, and switching means controlled thereby for disconnecting the rst controlling means from the line transmitting from A to B when said signals are transmitted over said line and from the line transmitting from B to A When said signals are applied to said line, said switching means controlled by said second controlling means being adapted to prevent the disabling of the line from B to A in response to the energy in the line from A to B or to remove such disability if it has already been applied, and similarly adapted to prevent or remove the disability of the line from A to B in response to energy in the line from B to A.

Y ELLIOT M. STAPLES. 

